This invention relates broadly to the art of valves, and more specifically to valves which are normally used for controlling the flow of granular, dried, or slurry materials (materials having a relatively high percentage of solids).
Traditionally, valves used for controlling the flow of materials having a high percentage of solids (35 percent or above), such as coal, fly ash (wet or dry) have employed ball, butterfly, plug, or linear slide-gate valve elements. A special problem which exists when one attempts to gate solid materials is that when the valving element is moved into the flow path of the material it urges the material against an opposite wall and thereby tends to jam the valving element open or to foul, or clog, its seat. For this reason, valves normally used for high percentage solid materials usually involve solid movable members with openings therethrough which are simply slid behind seals, out of the flow paths, to close the valves, rather than being pushed against a valve seat. Flow material which is in the opening of the valving element during a closing movement simply stays in the opening and is again picked up by material flow when the valve is again opened.
A very popular valve for valving high-percentage solid materials is a slide gate valve, one of which is described in U.S. Pat. No. 4,070,161 to Harter in which a reciprocally moving slide member is linearly moved to either the right or left by a rod to bring a hole therein into and out of registry with material flow. A significant problem with such valves is that they are quite long and take up a great deal of lateral space. Further, the slide members of such valves usually have seals and scrapers mounted thereon requiring a high degree of precision in construction and are, therefore, rather complicated to construct. Also, such valves require empty spaces in sealed housings which can become clogged with the flowing materials and which, therefore, can, and sometimes do, clog the valves. Thus, it is an object of this invention to provide a valve for controlling the flow of materials having high percentages of solids which takes up very little space, which has a relatively uncomplicated valving element not requiring special seals and scrapers, and which is virtually uncloggable.
Rotary valves are known in which rotary valving elements have holes therein for rotating into and out of registratry with flow paths. Several examples of these are described in U.S. Pat. No. 2,781,787 to Johnson; U.S. Pat. No. 3,779,510 to Krogsrud; U.S. Pat. No. 903,354 to Brown; and, U.S. Pat. No. 384,849 to Hood. Krogsrud (U.S. Pat. No. 3,779,510) is particularly relevant with regard to this invention inasmuch as it discloses a rotary valving element which is held in a gas-tight housing. However, most of these valves, including Krogsrud have complicated rotary valving elements which include such things as scrapers thereon to help clean seals. In this respect, most prior-art rotary valves, including those mentioned above, do not have easy-to-manufacture sealing arrangements between their valving elements and their housings or bodies. Thus, it is an object of this invention to provide a rotary slide valve which, in addition to providing the above benefits, has an effective sealing arrangement between a sealed body (housing) and a valving element which is uncomplicated to construct and assemble, constructed of inexpensive parts, is extremely effective in allowing easy rotation of the valving member, provides a seal with the valving member in either of opposite directions, and virtually makes impossible the clogging of the valve.
It is noted that the valve described in Johnson (U.S. Pat. No. 2,781,787) does not have a sealed housing and would therefore allow an unacceptable amount of leakage for some applications. It is an object of this invention to provide a turn disc slide valve which employs a sealed housing.